The complexity of the human proteome is presumed to encompass hundreds of thousands to several million different protein molecules. In terms of interpreting data, the situation is further complicated by the fact that the function of each protein found in multicellular organisms is not known and that there are various functions that depend on structural variations or interacting counterparts. Plus, the dynamic range of the protein expression is enormous.
In the case of antibody microarrays, antibodies are immobilized. After incubation with tissue lysate or serum, the binding of proteins to antibodies is either detected directly by the »staining« of the serum proteins or using appropriate detection antibodies. The fundamental structure here is consistent with a sandwich assay, just the same as with ELISA. In addition to antibodies, other classes of »binders«, such as aptamers or anticalins, can also be used for this purpose.
The aim of using antibody microarrays is to analyze variations in the actual protein incidence, in the occurrence of isoforms and other structural variations. The fundamental technical processes have been established at the institute, e.g. suitable surfaces, blocking of the surface to prevent nonspecific binding, as well as procedures that enable reproducible and reliable analysis. The antibodies are selected in cooperation with partner companies. In addition to the analyses using antibody microarrays, the transcripts can be identified with real-time PCR or physical parameters.